• NASA satellites observed greening during the 21st century
  • populous and developing countries
  • regions far removed from human reach

• Svalbard, in the high-arctic, 30% ↑ greenness
  • concurrent with ↑ in summer temperature from 2.9 to 4.7C

• What is the role of plants in global change?
  • question is a matter of scale

• Humans dump ~40 billion tons of CO₂ into atmosphere
  • EACH YEAR

• Atmospheric CO₂ is a greenhouse gas
  • ↑ CO₂ = ↑ trapped heat = ↑ surface temperatures

• Plants fix CO₂ from the atmosphere via Rubisco

• Ability to immediately fix carbon from atmosphere
  • photosynthesis - respiration
  • keeping pace with human emissions?

• Sequestrating carbon in wood
  • prevents fast cycling of carbon

• Transpiration adds H₂O into atmosphere
  • power greenhouse gas

• Are all trees carbon vacuums?
  • fast growing trees don’t live as long
  • fast growing trees drain more water
  • fast growing trees create less dense wood

• Farmland to forests: can we eat?

• Are all forests equal?
  • forest plantation = rain forest?

• Phenotypic plasticity: allows individuals to respond to change within their lifetime
  • acclimation (lifetime) vs adaptation (generations)

• Can plants change physiology to match new conditions?
  • can optimums be adjusted?

• Why might northern species struggle in warmer temperatures?

• Why might plants struggle in new precipitation regime

• Lots of other stresses on plant communities
  • impact sustainability of greening earth

• Habit degradation from human activities

• Total habitat loss
  • agricultural conversion
  • urban growth

• Higher rates of exotic species invasions

• Greening since 1980’s reduced warming ~0.2C

• New science suggests browning trend
  • greening trend stalling or reversing

• Related to less moisture in the air
  • higher VPD from climate warming

• Why would drier air impact plant growth negatively…

• Plant carbon sink does not fix global carbon imbalance